Different autophagic response and viability effect in hepatocarcinoma cell lines vs healthy controls upon oleic acid stimulation

Extra virgin olive oil is beneficial for health as it is associated with protection against liver steatosis, cardiovascular diseases and some types of cancer. These features are related to the presence of high levels of monounsaturated fatty acids including oleic acid (1). Here we study different responses between hepatocarcinoma cell lines (Hep3B and Huh7.5) vs a healthy hepatocyte control (THLE-2) following oleic acid treatment (OA; 50-300 μM). First of all, we observed a different neutral lipid accumulation between the hepatocarcinoma cells and the healthy control. We also found that, while hepatocarcinoma cell lines respond to dose-dependent OA treatment with autophagic flux reduction, healthy controls do not significantly modulate their autophagic flux. In order to better investigate the different autophagic response of Hep3B and Huh7.5 carcinoma cells as compared to THLE-2 cells, we analyzed the levels of perilipin-2 since it has been previously shown to have a crucial role in liver autophagy regulation. We interestingly found that in Hep3B and Huh7.5 carcinoma cells, but not in THLE-2 cells, dose-dependent OA treatment is associated to significant increasing perilipin-2 levels. Such results are in agreement with previous studies showing and inverse relationship between perilipin-2 and autophagy levels (2). Moreover, we found a differential viability rate: a reduction of hepatocarcinoma cell lines at 300 μM OA dosage but unchanged vitality in healthy hepatocytes through Alamar Blue staining. Furthermore, in preliminary experiments aimed at evaluating the apoptotic rate by western blot, we found increased levels of cleaved caspase-3 in Huh7.5 but not in Hep3B and THLE-2. Further experiments are ongoing to i) investigate cell death mechanism in Hep3B and ii) manipulate autophagy in order to investigate at molecular level the beneficial effects of OA in counteracting hepatocarcinoma.